As one of atomic absorption spectrophotometers, there is an atomic absorption spectrophotometer using a tube-like furnace made of graphite. In such an atomic absorption spectrophotometer, a sample is injected into a furnace from a small hole provided in the furnace using an instrument such as a syringe needle, and then the furnace is heated according to a predetermined temperature program to atomize the sample. At this time, measurement light from a light source composed of a hollow cathode lamp is irradiated in the furnace, passed through the atomic vapor, and the transmitted light is detected by a detector. Thus, the absorbance to a specific wavelength by the atomized sample component is measured (see Patent Document 1)